Volume control



June 6, 1933. F; NC LA; 1,912,719

VOLUME CONTROL Filed June 19, 1951 75 Source of flzzac'o fieyaency Enezyy INVENTOR PAUL NlCOLAS BY/tQZQ/W ATTORNEY Patented June 6, 1933 UNITED STATES PATENT OFFICE PAUL NICOLAS, OF PARIS, FRANCE, ASSIGNOR TO COMPAGNIE GENERALE DE TELEGRAPHIE SANS FIL, A CORPORATION OF FRANCE VOLUME CONTROL Application filed June 19, 1931, Serial No. 545,385, and in France July 3, 1930.

The present invention relates to improvements in the means, or devices, used for volume control, which, by being combined with, or added to, amplifiers for telephone,

voice or musical currents, serve to regulate the intensity, or volume, of sound generated by the reproducer apparatus.

It has previously been suggested in the art, with the same end in view, to use potentiometric resistances. However, if satisfactory results are to be obtained, especially from the viewpoint of quality of reproduction, it is necessary to adopt a number of precautionary measures.

The present invention concerns a potentiometric device adapted to be inserted between a source of audible currents (say, a pick-up, photo-electric cell generally associated with an input amplifier device), and

the input of the next amplifier stage, to the output end of which is connected the generator, or reproducer, of sound, as for example a loud speaker.

The same consists in combining with the potentiometric resistance, connected across the terminals of the audible current, of resistances in series with each of the terminals or taps of the potentiometer, said resistances having such a value that the resistance of the circuits as thus arranged, and connected across the input terminals of the amplifier will be constant, regardless of what may be the particular setting of the potentiometer.

The novel features'which I believe to be characteristic of my invention are set forth in particularity in the appended claims, the invention itself, however, as to both its organization and method of operation will best be understood by reference to the tel- 40 lowing description taken in connection with the drawing in which I have indicated diagrammatically several circuit organizations whereby my invention may be carried into effect.

The invention will be more clearly understood by reference to the attached drawing, and the following detailed description, wherein,

Fig. 1 shows the basic principle underlymg the invention,

Fig. 2 is a special embodiment preferably suited for present-day practice.

A volume control, according to this invention, comprises, as in Fig. 1, between the input terminals A and B adapted to be connected with the source of audible current, a potentiometer divided by a tap, such as indicated at X, into two parts having values R and R. The output terminals C and D being adapted to be connected with the amplifier, a resistance R is included between points X and D, this resistance having such a value that the resistance between C and D will be constant, irrespective of what may be the position of the point, or slide, X beas tween A and B.

A simple calculation will demonstrate that the expression for the resistance between the points C and D is R R constant B (1) Z represents the impedance of the audible source (or audio frequency source) disposed between A and B. From the said expression it is possible to directly infer the value of R" imposed by the invention.

A special and simplified embodiment of the scheme of this invention (Fig. 2) con- 30 sists in constituting a volume control by means of a potentiometric resistance comprising a plurality of like resistances, each having value 7 disposed in series, between the input terminals A and B. In the shunts X1 and D1; X2, D2; X3, D3; Xn,.Dn connecting the various potentiometer taps with the output terminals of the apparatus, are inserted resistances having the respective values 1", 2?, 3r m". o

This particularly simple embodiment is feasible whenever there is an abundant energy in the source available, for in this in stance it is possible to connect in series therewith a resistance of high value. In order to maintain theresistance across the terminals CD practically at a constant value, it will then be sufficient to make R equal to B so that in the circuit DXC the sum total of the resistances in series remains constant, and

equal to the potentiometer resistance between A and B.

lVithout departing from the scope and spirit or this invention it would obviously be possible, also, to choose for the said constant value of the circuit DXC a value differing from the resistance AB. It will be understood that this invention-is capable of a great number of modifications, especially in so far as the values, forms, nature and arrangements of the resistances used is concerned, and also as regards the types of contacts and slides or contact pieces that are adopted.

Vhile I have indicated and described several systems for carrying my invention into effect, it will be apparent to one skilled in the art that my invention is by no means limited to the particular organizations shown and described, but that many modifications may be made without departing from the scope of my invention as set forth in the appended claims.

lVhat I claim is:

1 A potentiometric arrangement adapted for use with a source of audio frequency energy to be amplified and reproduced and an amplifier for said energy, said arrangement comprising a pair of terminals adapted to be connected to said source and a second pair of terminals adapted to be connected to said amplifier, a resistor connected between said first terminals, said source having an impedance Z, a first connection between one side of said resistor and one of said second terminals, 21 second connection between the other of said second terminals and an inter mediate point of said resistor, said intermediate point dividing said resistor into portions R and R, and a second resistor R in said second connection have a magnitude such that the resistance R between the second pair of terminals is a constant regardless of the position of said intermediate point, said magnitude being determined by the following equation:

2. A potentiometric arrangement adapted for use with a source of audio frequency energy to be amplified and reproduced and a amplifier for said energy, said arrangement comprising a pair of terminals adapted to be connected to said source and a second pair of terminals adapted to be connected to said amplifier, a resistor connected between said first terminals, said source having an impedance Z, a first connection between one side of said resistor and one of said second terminals, a second connection between the other of said second terminals and an intermediate point of said resistor, said intermediate point dividing said resistor into portions R and R, and a second resistor R in said second connection having a magnitude such that the resistance R1 between the second pair of terminals is a constant regardless of the position of said intermediate point, said magnitude being equal to the magnitude of R.

3. A potentiometric arrangement adapted for use with a source of audio frequency energy to be amplified and reproduced and an amplifier for said energy, said arrangement comprising a pair of terminals adapted to be connected to said source and a second pair of terminals adapted to be connected to said amplifier, a resistor connected between said first terminals, said source having an impedance Z, a first connection between one side of said resistor and one of said seconn terminals, a second connection between the other of said second terminals and an intermediate point of said resistor, said intermediate point dividing said resistor into portions R and R, and a second resistor R in said second connection having a magnitude such that the resistance R between the second pair of terminals is a constant regardless of the position of said intermediate point, said magnitude being equal to the magnitude of R and a plurality of addi tional terminals between the second pair of terminals, connections from said additional terminals to points on the first resistor dividing the portion R into equal portions each having a value equal to the magnitude of R, and a resistor in each of said addi tional connections, said additional connec tion resistors increasing in value towards said first connection and each having a value equal to a multiple of said second connection resistor.

PAUL NICOLAS. 

